Metagenomic insights into the effects of ecological water replenishment on resistome and pathogens in urban wetland

Abstract

Urban wetland restoration increasingly relies on water replenishment, yet its impacts on resistome dissemination remain critically understudied. Here, we performed a comprehensive metagenomic survey of water and sediment from the Xixi National Wetland Park to investigate how water diversion from the surrounding Qiantang River affects the distribution and composition of antibiotic-resistant genes (ARGs), mobile genetic elements (MGEs), virulence factors (VFs), and pathogens. Among the detected ARGs, multidrug, macrolide-lincosamide-streptogramin, and bacitracin resistance genes were predominant. MGEs such as tnpA, IS91, and istA, and VFs involved in adherence and immune modulation were also abundant. Pathogens including Fusobacterium varium and Leptospira noguchii were frequently observed. RDA and MRM analysis revealed certain antibiotics emerged as influent factors of resistome composition. Notably, the vast majority of resistome types were shared between the wetland park and the external riverine environment, with a decline in resistome richness as distance from the water diversion source increased. This phenomenon indicates that river-to-wetland water diversion acts as a conduit, facilitating the broad dissemination of resistome components and pathogens into the wetland, while the wetland’s self-purification capacity also plays a role. Nevertheless, a small subset of ARGs and MGEs was significantly enriched within the wetland interior. Collectively, these results highlight the ecological risks of water replenishment in urban wetlands and underscores the need for mitigation strategies, such as source-water pretreatment and wetland sediment remediation.